Evaluation and Management of Hypertrophic Cardiomyopathic Patients Through Noncardiac Surgery and Pregnancy

Abstract

Due to the prevalence of hypertrophy cardiomyopathy (HCM) (1:500), anesthesiologists, cardiologists, surgeons, and obstetricians will encounter these patients and need to thoroughly understand their disease in order to understand the risk that noncardiac surgery and pregnancy imposes upon them. Patients with HCM have genotypic and phenotypic variability. Indeed a subgroup of these patients exhibits the HCM genotype but not the phenotype (left ventricular hypertrophy). There are a number of treatment modalities for these patients including pharmacotherapy to control symptoms, implantable cardiac defibrillators to manage malignant arrhythmias, and surgical myectomy and alcohol septal ablation to decrease the left ventricular hypertrophy and outflow obstruction. In this chapter, we will discuss how management of these patients perioperatively is vital to improving their survivability and morbidity when they undergo noncardiac surgery, either electively or emergently. We will also discuss the peripartum management of the HCM patient since the physiologic changes of pregnancy can have either a salubrious or detrimental effect on the pathophysiology of HCM.

This work was supported in part by a grant from the National Institutes of Health (HL098046).

Questions

• 1. Which pressure gradient across the left ventricular outflow tract (LVOT) is considered significant for septal reduction therapy if a HCM patient is still symptomatic despite maximal medical therapy?

  • A. Mean pressure gradient ≥30 mm Hg

  • B. Mean pressure gradient ≥50 mm Hg

  • C. Peak pressure gradient ≥20 mm Hg

  • D. Peak pressure gradient ≥30 mm Hg

  • E. Peak pressure gradient ≥50 mm Hg

  Answer: E. HCM patients with significant LVOT obstruction, peak pressure gradient ≥50 mm Hg, and symptomatic despite maximal medical therapy should be evaluated to be a candidate for septal reductoin therapies. Surgical myectomy, the gold standard for intervention by the American Heart Association and American College of Cardiology consensus guidelines, is a first option, although many patients may elect for alcohol septal ablation if available and indicated given the need for a second surgery. Due to the nature of late-systolic obstruction in HCM patients, only the peak pressure gradient is evaluated to determine candidacy.

• 2. How does atrial fibrillation affect the perioperative risk of HCM patients?

  • A. It is the same degree of risk for all atrial fibrillation patients, regardless of whether they have HCM or not.

  • B. Since all HCM patients are very preload sensitive, those in atrial fibrillation need increased preload during their perioperative period.

  • C. HCM patients rarely have atrial fibrillation since the more prominent arrhythmias are lethal ventricular arrhythmias.

  • D. Due to the reduction in cardiac output by approximately 40%, HCM patients that go into atrial fibrillation during the perioperative period are at increased risk of intravascular volume overload.

  • E. They are only at an increased risk for perioperative stroke.

  Answer: D. Atrial fibrillation is a strong predictor of mortality, even after adjustment for established risk factors in a recent study [26]. HCM patients with atrial fibrillation (AF) are at increased perioperative risk due to HCM-related factors and atrial fibrillation-related factors. This is due to the loss of atrial kick in those with diastolic dysfunction and hypertrophied left ventricles, which may cause a loss of 40% of their cardiac output. This places HCM with AF at increased risk for intravascular volume overload and perioperative heart failure exacerbations.

• 3. An HCM patient presents in the preoperative area for an atrial fibrillation ablation and pulmonary vein isolation. He is noted in cardiology reports to have a peak pressure gradient across the LVOT of 102 mm Hg 2 years ago. No recent TEE has been done. The patient has become increasingly symptomatic with dypsnea on exertion despite maximal medical therapy and now has increasing periods of paroxysmal atrial fibrillation. What is the best management for this patient?

  • A. Proceed with ablation procedure, explaining to patient that due to their last LVOT gradients, they are at much higher perioperative risk.

  • B. Explain to patient that since they have significant LVOT pressure gradients and are failing maximal medical therapy, they would be a candidate for either surgical myectomy (gold standard) and may have a modified MAZE procedure during the time of their surgery. In the meantime, ensure patient is started on rate and rhythm control medication.

  • C. Cancel the EP procedure due to no recent TEE and patient’s symptomatology.

  • D. Proceed with cardioversion, despite no TEE, and reschedule EP ablation.

  • E. B and C are correct.

  Answer: E. Ideally, this patient would have a recent TEE given a history of significant LVOT gradients to 102 mm Hg 2 years ago and a recent change in symptomatology. Due to the continued increased LV intraventricular pressure across the LVOT, resulting in a higher LVEDP and left atrial pressure, the ablation has a higher risk of failure. The patient should be initiated on rhythm control medications and referred to a high-volume surgical center for myectomy. The patient may be a candidate for a modified MAZE or MAZE procedure with left atrial appendage ligation at the time of myectomy [8].

• 4. An HCM parturient G3P2 presents in labor and delivery after spontaneous rupture of membranes. She is having regular contraction 2 min apart that lasts 1 min, and she rates her pain as 9/10. She is interested in having an epidural. What are the next best steps?

  • A. The anesthesiologist proceeds to place a lumbar epidural giving normal doses of local anesthetic since the patient is in 9/10 pain.

  • B. The anesthesiologist explains to the patient that since she has HCM, she cannot labor and must go to the OR for urgent cesarean section.

  • C. After obtaining a thorough history, including her most recent TEE report, that shows a peak pressure gradient of 50 mm Hg, and her functional status – NYHA Class II (the patient has continued on beta-blockade throughout pregnancy), the anesthesiologist discusses the patient’s increased risk and need to place an intra-arterial monitor prior to placement of the epidural catheter. Careful titration of local anesthetic occurs to obtain an appropriate anesthetic level.

  • D. Multidisciplinary discussion with anesthesiology and obstetrics regarding the patient’s attempt at trial of labor and if there is hemodynamic instability with continued Valsalva during stage 2 of labor, then it may necessitate vacuum-assisted or forceps delivery.

  • E. Both C and D are correct.

  Answer: E. HCM parturients can do well during pregnancy and peripartum. Studies have shown this is highly correlated with the degree of heart failure or NYHA class that the patient experienced prepregnancy [29, 30]. HCM is not an indication for cesarean section . Cesarean sections should only be performed in those patients that present in heart failure and are too hemodynamically unstable to undergo vaginal delivery. In HCM parturients, especially those with significant gradients, it is prudent to place intra-arterial pressure monitors prior to placing epidural catheters. Judicious fluid therapy may be given prior to dosing the epidural with local anesthetic to ensure optimal left ventricular filling pressures. Slow titration of local anesthetic is recommended. Second-stage vacuum-assisted or forceps delivery may be considered to prevent increasing LVOT obstruction if there is hemodynamic instability with continued Valsalva maneuvers.

• 5. What is the most significant predictor of how well HCM patients can tolerate noncardiac surgery?

  • A. No significant LVOT obstruction

  • B. Less than moderate mitral regurgitation due to systolic anterior motion of the mitral valve

  • C. No history of previous ventricular arrhythmias

  • D. NYHA classification

  • E. Left atrial indexed diameter < 3.0 cm²

  Answer: D. According to a recent retrospective review of HCM patients undergoing noncardiac surgeries at a high-volume center, the most significant predictor of how well patients will do is their NYHA classification preoperatively [2]. Those with NYHA I–II classification safely underwent noncardiac surgery, even though the majority of patients received vasoactive medications intraoperatively. Those that had noncardiac surgery emergently had a significantly higher associated risk of death (p = 0.0002) [2].